git stash apply leaves entries in place, so later stashing can restore the wrong changes; git stash pop applies and removes the top stash entry.

Flaky test suites can fail more often with too many parallel workers; limiting PARALLEL_TEST_PROCESSORS can reduce race-condition failures with only a small runtime cost.

Selenium can fetch binary files through JavaScript and return them to Ruby as an array, useful when direct downloads are awkward or blocked.

Quick reference for native DOM methods and properties that replace many jQuery calls, helping you find equivalents without browsing Element interfaces.

Rails apps can make hidden file checks that slow requests, especially on networked storage. strace reveals unnecessary stat calls and other system calls.

Git pushes can trigger unwanted CI jobs on GitLab, GitHub Actions, or Travis CI. Skip runs with commit-message flags or GitLab push options.

Bundler can install different gem variants depending on Gemfile.lock platforms, causing inconsistent native package versions. Locking the target platform improves reproducible installs.

Nokogiri can be built against system libxml2 instead of bundled binaries, reducing rebuild work after security updates and aligning installs with patched OS libraries.

Chrome DevTools can switch between vertical and horizontal panel layouts based on width, making deep DOM trees hard to inspect. The panel layout setting forces a preferred orientation.

Capistrano stores the deployed commit hash in REVISION, making the live release easy to identify on one server or across multiple hosts.

Delays repeated function calls until activity stops, reducing work from noisy events like scrolling and improving performance.

Installing the newest RubyGems can break older Ruby versions; use the latest compatible release instead of the default system update.

Move API-client code out of app/models into lib/ to separate domain logic from reusable infrastructure and keep Rails code more maintainable.

Configuring a Ruby library via a block makes endpoints and similar settings easy to override without hardcoding values.

MySQL can ignore indexes when a predicate compares a column to the wrong data type, turning lookups into full table scans.

RSpec hook order matters when around(:all) and around(:each) wrap setup and teardown; their execution timing differs from before and after hooks.

Ruby classes with many fields can become hard to instantiate or validate. Options range from positional and keyword arguments to ActiveModel::Attributes, Struct, hashes, and OpenStruct.

Fresh Chrome installs in Europe can trigger a search-engine choice popup that breaks Cucumber tests; --disable-search-engine-choice-screen disables it.

cucumber_factory 1.14 adds array attributes, multiple has_many associations, and unquoted numeric values in factory-style test data.

Rails error messages can be overridden at application, model, or attribute scope through locale YAML files, enabling clearer validation feedback than the default generic texts.

Rails environment code loads in a fixed boot order, affecting which settings and constants can override others. Knowing the initialization sequence prevents surprises when adding configuration or app code.

params can contain nil, arrays, or hashes, so treating request values as plain strings can lead to unsafe lookups and unexpected matches.

{} and do ... end bind blocks to different method calls, which can make print names.map do ... end return an Enumerator instead of the mapped array.

Tod handles time-of-day values without dates, avoiding timezone-related bugs when parsing, comparing, formatting, or storing hours, minutes, and seconds.